1. Field of the Invention
This invention relates to a novel oil-in-water insecticidal and acaricidal emulsion (generally called an "aqueous flowable formulation"), which comprises as a hydrophobic insecticidally and acaricidally active liquid ingredient 1 to 50% by weight of at least one ester of the formula (I): ##STR4## where X is a hydrogen atom, a chlorine atom, a bromine atom or a fluorine atom; and Y is a group of the formula: ##STR5## where R.sub.1 is a methyl group or a group of the formula: ##STR6## where R.sub.5 is a chlorine atom, a bromine atom, a fluorine atom or a methyl group; R.sub.2 is a hydrogen atom or a methyl group; R.sub.3 is a chlorine atom, a bromine atom, a fluorine atom or a tert-butyl group; and R.sub.4 is an isopropyl group or a cyclopropyl group, 2 to 10% by weight of polyvinyl alcohol or gum arabic; and 0.1 to 20% by weight of a thickener with the balance being water. The insecticidal and acaricidal emulsion of the invention exhibits an insecticidal and acaricidal activity equivalent to a conventional formulation and at the same time it is stable and easier to use.
2. Description of the Prior Art
Of conventionally employed pesticidal formulations in a liquid form, an emulsifiable concentrate which generally consists of a pesticidally active ingredient, a synthetic surfactant and a large amount of an organic solvent often has defects derived from the organic solvent contained therein, such as flammability or malodor, toxicity or irritation to humans, cattle or other domestic animals or poultry, phytotoxicity against crops, and the like.
A wettable powder which does not use an organic solvent is also not fully satisfactory because a spray liquid cannot readily be prepared due to dustiness of its fine powder and aerial low volume application in high concentration (less than 300 ml per 10 ares) is impossible.
For these reasons, studies have been made on aqueous flowable formulations of pesticides and transparent emulsions which replace the organic solvent or powder carrier with water to suspend or disperse fine particles of a hydrophobic pesticidally active ingredient.
Since such aqueous flowable formulations and transparent emulsions are handled in a liquid form, a spray liquid can be prepared without producing dust; and measuring the volume, dilution and other necessary operations can be achieved as easily as with conventional liquid type formulations. In addition, it is accompanied by few or none of the problems of an organic solvent which is toxic or irritating to humans, cattle or other domestic animals or poultry, as well as causes phytotoxicity against crops. However, most aqueous flowable formulations of pesticides hitherto proposed are suspensions using a solid hydrophobic pesticidally active ingredient (such as those disclosed in Japanese Patent Application (OPI) Nos. 126635/74, 76236/75 and 148625/77 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"); and U.S. Pat. No. 4,071,617), and no practical oil-in-water emulsion that uses a pesticidally active ingredient in an oil form has yet been developed due to difficulties in stabilizing its physical properties over an extended period of time.
Transparent emulsions used as oil-in-water pesticidal compositions are disclosed in Japanese Patent Publication No. 20520/71, and Japanese Patent Application (OPI) Nos. 54547/74 and 122628/77, but these transparent emulsions are a water soluble type that uses a large quantity of a general-purpose synthetic surfactant to reduce the particle size of the pesticidally active ingredient to less than 0.1.mu., and no satisfactory technique has been proposed to solve the cost and toxicity problems which accompany the use of large quantities of surfactant.